MsgBox & Inno Setup

Hi Dears,
I want to Deploy a Project using Inno Setup
what i want is:

MsgBox With OKOnly Button Appear Before The Setup Start

i tried this:
===============
function MsgBox(const Text: String; const Typ: TMsgBoxType; const Buttons: Integer): Integer;

begin
// Display a simple message box with an OK button
MsgBox('Hello.', mbInformation, MB_OK);

===============
But it doesnt Work

is it Impossible to do this Function With Inno Setup ? ??